Got it taken care of today. I hope.
Firstly (according to this shop, the place that set them was all wrong. Turns out the numbers I am seeing should and actually do match the boot length. They are not prefect exact but they (in the end) set them a hair past 334 (about 335 to take a guess). so I don't understand how that original shop set them up to 342. To recall, my boots are stamped 336 so this does seem more correct.
They (this shop today) set my DIN at 8 and also did the force checks and all is now OK according to them. Front and rear releases at that setpoint. Told me they would have surly released much too early had I left the length at 342 with the same 8 DIN setting. I actually had them set at din of tad over 7 so between that and also the original longer length setting I would have been popping out.
As for the screw in the rear bottom, he said these are a little different than other marker bindings. and (when the boot is snapped in) the flat part should be slightly submersed into the binding (not even with it) and the groves (threadlike part) should be what you see sticking out. And after the new settings and release pressure checks were done this is pretty much where the screw like piece now sits when boot is engaged.
I don't know how one shop can say one thing and another something different? To be honest all the numbers on the ski and binding seem to be what they actually mean which all "seems" like this place got it right.
Had I not had this checked and went skiing and started popping out early I would have just cranked up the DIN and I wonder how wrong that all would have been?
In one sence I question which shop was correct and sinse this latest one does actually closer line up with the numbers on the skis and then checks out correct I have to assume its OK now and was not before. The only thing now I question a tiny bit is that the boot (rear tab) barely slips past the (open) rear binding before resting , where as before there was a little space between the rear boot tab and the binding while the boot rested in the binding. And I thought that there should be some space (perhaps 1/4") before snapping in so I still have "some" small doubt in my head. But they guy said no that's fine and it all is good now. I just think about the ability for the ski to flex which means it should be able to move the bindings in and out at least a little bit no? but then I guess if the boot is releasing at the same force as what the DIN number is set than it must be OK.? As you can see I go back and forth in my head with this. I just want it right.
The original shop I bought the skis fromis "Colorado ski shop" which is in VT. and also MA in case anyone is familiar with them. The place that re-set me up today was a "Ski Barn" a small chain in Jersey and the workers are knowledgeable, especially the gentlemn I dealt with today and was very confident in what they did and when explaining it to me..